An automatic analyzer measures measurement items such as biochemical test items and immunological test items. The automatic analyzer dispenses a sample and reagent corresponding to each measurement item into a cuvette, and stirs them. When the sample and reagent are stirred, a mixed liquid causes a chemical reaction, for example, its color tone or turbidity changes. The automatic analyzer measures this change in color tone or turbidity by measuring a light transmission amount, thereby measuring the concentrations of various components and the activity of an enzyme in the sample. After measurement, the mixed liquid is disposed. Then, the cuvette of the mixed liquid is cleaned with a cleaner and water by cleaning nozzles, and is dried by a drying nozzle. The dried cuvette is used again in measurement.
Optimal cleaning patterns of the cuvette are different depending on measurement items, that is, samples and reagents. Note that the cleaning pattern specifies, for example, the types, the numbers of times of use, and the use order of cleaning liquids to be used. However, sharing roles of respective cleaning nozzles are fixed. That is, the cuvette is cleaned according to a given cleaning pattern irrespective of the types of samples and reagents. Therefore, the cuvette cannot often be cleaned according to a cleaning pattern optimal to a measurement item, and improvements of the cleaning precision and cleaning efficiency of the cuvette are demanded.
When the cleaning nozzle is inserted into or pulled out from the cuvette, for example, the cleaning liquid and mixed liquid contained in the cuvette are spattered from the cleaning nozzle, and often enter into another cuvette. Due to mixture of the cleaning liquid into the cuvette, the cleaning precision and cleaning efficiency of the cuvette deteriorate.